1. Technical Field
The present invention relates to a color image pickup device, an imaging apparatus and a control program for an imaging apparatus, and in particular to a color image pickup device that includes phase difference detection pixels and to an imaging apparatus and a control program an imaging apparatus of the same.
2. Related Art
For solid state image pickup devices installed in imaging apparatuses such as digital cameras, there are those that, in order to raise Auto Focus (AF) performance have phase difference detection pixels as a portion of the pixels out of many pixels formed on the solid state image pickup device light receiving surface (see for example Patent Documents 1 to 7).
The phase difference detection pixels are, for example as in the Patent Documents 1 to 7 listed below, configured by 2 nearby pixels mounted with the same color filter to form pairs, and are provided with light-blocking film openings that are respectively smaller than the light-blocking film openings provided to normal pixels. Moreover, the light-blocking film opening provided to one of the phase difference detection pixels configuring a pair is provided eccentrically in a separation direction (for example on the left side) from the other phase difference detection pixel, and the light-blocking film opening of the other phase difference detection pixel is provided eccentrically in the opposite direction (for example on the right side).
During AF operation in an imaging apparatus, the signals are read from the phase difference detection pixels of the solid state image pickup device, a focal point shift amount is derived from the detection signal of the pixel with light-blocking film opening eccentrically placed on the right side, and the detection signal of the pixel with the light-blocking film opening eccentrically placed on the left side, and the focal position of the imaging lens is adjusted.
The precision of such AF operation is higher the more there are of the phase difference detection pixels, however during main image capture of a normal subject image, the phase difference detection pixels have narrower light-blocking film openings and lower sensitivity, and hence there is the issue that they cannot be treated in the same way as normal pixels.
Accordingly, during reading out signals from all the pixels and generating a subject image, there is a need to perform gain correction on detection signals from the phase difference detection pixels to a similar level to the sensitivity of the normal pixels, or to treat the phase difference detection pixels as missing pixels and to perform interpolation computation correction using the detection signals of peripheral normal pixels.
Patent Documents
Patent Document 1Japanese Patent Application Laid-Open (JP-A)No. 2000-156823Patent Document 2JP-A No. 2007-155929Patent Document 3JP-A No. 2009-89144Patent Document 4JP-A No. 2009-105682Patent Document 5JP-A No. 2010-66494Patent Document 6JP-A No. 2008-312073Patent Document 7Japanese Patent No. 3592147
In such AF operation, although the precision is raised the greater the number of phase difference detection pixels, during normal subject image main image capture, the phase difference detection pixels have narrower light-blocking film openings and lower sensitivities, and there is the issue that they cannot be treated the same as normal pixels, and hence the number of phase difference detection pixels cannot be increased excessively. Also, in cases in which the colors of normal pixels adjacent to respective phase difference detection pixels configuring a pair are different from each other, sometimes color mixing occurs and there is a deterioration in AF precision.